I get Object Reference not set to an instance of an object error with that line. Shouldn't that create a new instance of the object if it doesn't already exists? This has been my experience when using that with ViewModels.

I'd like to reference the instance in other areas of my app like this:

Is your catalog setup properly? I mean, are you sure that the IoC is able to locate the export (i.e you created a proper catalog for the external assembly or you added the Infrastructure Assembly to the AssemblySource.Instance collection)?